Page Decomposition

In positioning mode, the image processor performs a page detection, extracts the subimage and places it on a clear, white canvas. This will be the output image.

To turn the positioning mode on, check the Page Content Detection check box on the Page Setup page of the main window.

Now we are going to discuss the page detection options that apply to the positioning mode only. The most important options are the margins located on the Margin Setup page of PPP. The margin dimensions are always measured from the edges of the output canvas. The function of the margins is two fold. The first function is to determine whether the subimage is inside or outside of the margins. If the subimage is out of the margin, the image processor will generate an exception. The second function of the margins is related to the subimage alignment. The horizontal and the vertical alignment can be specified independently and the subimage can be aligned to any of the margins, to the center of the output canvas, or its position can remain unchanged.

Recto - Verso

There are two different margin modes. In simple margin mode, the same margins will be applied to odd and even pages. In odd-even margin mode, different values of margins will be used for the odd and even pages.

If odd-even margin mode is selected, PPP uses the image file name to determine whether the image is odd or even. If the last digit of the image file name is odd, the image is considered an odd page. If the last digit is even, the image is processed an even page.

Consider the following example. You have the following image files in the Selected Files List: img01.tif, img02.tif, img03.tif, image16.tif. In this case, img01.tif and img03.tif will be treated as odd pages, while img02.tif and image16.tif will be processed as even pages.

The odd-even margin mode also affects the Edge cleanup parameters. Different values can be specified for the odd and the even pages in odd-even mode.

Page Detection Style Sheets

The second positioning parameter is the page detection style sheet, which affects the behavior of the page detector engine. The engine has a variety of parameters organized into style sheets. A style sheet fully describes the behavior of the page detector. Style sheets are identified by their names. So when you need to specify the page detection behavior, you just select the name of the style sheet on the Page Setup page.

The default style sheet is the Factory settings style sheet which comes with PPP. These are read-only parameters. They cannot be changed. Factory settings are worked out for the following resolutions: 200, 300, 400, 500, 600, 700 and 800 DPI. Your own custom style sheets should also be worked out for these resolutions.

Note that sometimes a style sheet does not support all resolutions. If a style sheet does not support the resolution of your input image, the page detector engine will automatically use the Factory settings. In this case, no exception will be generated.

Controlling Subimage Size

The last settings on the Page Setup page are the Maximum subimage size parameters. They limit the maximal size of the subimage. If a subimage is larger than the specified dimensions, an exception will be generated.

Cleanup Parameters

Keep contents outside detected subimage

By default, Keep contents outside detected subimage is turned off. In this case the image processor will only place the subimage on the new canvas, and the area outside of the subimage will be white and perfectly clear, thus removing the speckles and connected pixel areas that don't qualify as part of the detected image.

If this parameter is turned on, the image processor will keep the content of the input image, including the area outside the subimage. This option does not change the behavior of the page detector. The page detection will be performed independently from the Keep contents outside detected subimage option. The only difference is that the subimage will not be cropped when the Keep contents outside detected subimage option is turned on. Instead, the image processor will place the whole input image on the output canvas, including the area outside of the detected subimage.

The output image position will be determined based on the detected subimage in both cases. If Keep contents outside detected subimage is turned on, some portions of the input image may stick out of the margins, or even out of the output image. However, the subimage itself must always fit between the margins, otherwise the file will be directed to the Exception List.

Subimage is less than

If this option is turned on, you can specify the minimal size of the subimage. If the subimage is too small, an exception will be generated. If this option is turned off, no exception will be generated, even if the input image is totally clear. In this case, the output image will also be clear.

Operation performed by the image processor on each image in positioning mode:

See also:

Setting Canvas Size

Setting Deskew

Setting Edge Cleanup Parameters

Setting Margins

Setting Page Detection Parameters

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